EP1467091B1

EP1467091B1 - Floating water current turbine with counter rotating coaxial rotors

Info

Publication number: EP1467091B1
Application number: EP04015814A
Authority: EP
Inventors: Svein Henriksen
Original assignee: Hydra Tidal Energy Technology AS
Current assignee: Hydra Tidal Energy Technology AS
Priority date: 2001-07-11
Filing date: 2002-07-08
Publication date: 2012-02-29
Anticipated expiration: 2022-07-08
Also published as: DE60203516D1; JP4309258B2; EP1467091A1; RU2004103865A; PT1415087E; CA2453401C; RU2301911C2; US20050236841A1; NO20040132L; EP1415087A1; ES2240768T3; EP1467092A3; DK1467091T3; AU2007203437A1; CA2453401A1; RU2006105189A; NZ530506A; AU2002318086B2; ATE292240T1; US20090058090A1

Abstract

The present invention comprises a rotating member (400) designed for rotation actuated by currents in the body of water so as to function as energy supplier in a generator unit located in a body of water. The rotating member, as illustrated in Figure 7, is built up around a shaft (405) which is mounted (preferably at right angles) on a hub on the generator shaft. The rotating member according to one embodiment of the invention comprises an inner end piece (407) mounted on the shaft (405) at the attachment of the shaft to the hub, a tip (406) mounted at the outer end of the shaft, and a plurality of member sections (410) rotatably mounted on the shaft (405) between the end piece (407) and the tip (406). <??>Each member section (410) is individually selectively pivotal and adjustable about said shaft, in order that the rotating member as such can assume the optimal pitch in relation to the water current. <IMAGE> <IMAGE>

Description

Technical field

The invention relates to apparatus for extracting energy from water currents. More specifically, the invention relates to a floating plant for the production of energy from currents in a body of water, as disclosed in the preamble of independent claim 1. The plant utilises currents below the surface of oceans, seas, rivers or other bodies of water. Such currents may, e.g., be caused by tidal variations and/or underwater topography (e.g., channels, riverbeds or other narrow passages under water).

Background art

Current in large bodies of water, as for instance that generated by tidal variations, is a renewable source of energy which thus far has not been exploited in Norway. This is the case even though such currents are highly predictable and readily available per se along the Norwegian coast.
When currents in large bodies of water (e.g., oceans or rivers) are forced through channels or other narrow passages, the velocity of flow will increase and will to a very great extent be aligned. The current in the central region of the narrow passage will have an almost equal velocity across the whole of the cross-section in question, which means that it is advantageous to position a power generator in this region.
There are a number of known apparatus and methods for the production of energy from ocean currents.
GB 2 347 976 discloses a twin turbine assembly arrangement including turbines with rotors incorporating pitch control. In this arrangement the turbines nacelles and the rotors are attached to a cross arm via a torque tube, which runs through the cross arm and past one side of a column. If desired two columns may be installed in such a manner that they support a much wider horizontal arm that can carry as many as for example five variable pitch rotor assemblies. Thus two columns are arranged side by side and then linked together with an appropriately long cross arm carrying five turbine assemblies. A system of this kind is intended for use in shallow water where lack of depth requires the use of amll rotors to gain the required power, rather than the use of one or two larger rotors.
GB 2 311 566 discloses a column mounted water current turbine, which has a nacelle shaped turbine housing and a turbine rotatably mounted to a column. The assembly comprises a turbine mounted for operational cooperation with a flow of water by means of an upstanding column. The assembly may rotate about the axis of the column, allowing the rotor to align itself with the flow of water. The turbine can be raised or lowered with respect to the column and also the surface of the water. If desired, multiple rotor installations can be used. Figure 8 shows schematically a twin rotor installation in which two or more rotors are mounted upon horizontally streamlined support members.
US 4,864,152 discloses a floating water current power station comprising a ring-shaped pontoon, which by means of an upright buoy is anchored to anchors. All the turbines are detachably arranged on a common beam, and can as a unit be swung up to the surface within the area limited by the ring pontoon. The power station may swing around the buoy, the upper end of which is connected to a front pontoon, and a lower end of which is secured to the anchors. The buoy is moreover provided with tension distributing warps to the turbine beam, and warps to the same pontoon side as the one to which the buoy is secured.
Norwegian Patent Application 1999 1984 (Hammerfest Strøm) describes a plant for the production of electric power from ocean and river currents. The whole of the plant is located below the surface of the water and comprises a plurality of turbines having blades, a support system, a system of stays and a generator. The turbine shafts are oriented perpendicular to the direction of movement of the water, and the blades are wing-shaped so that the turbine rotates in the same direction, regardless of the direction of movement of the water. The turbine shafts are supported in a framework of buoyancy tanks, secured to the support and bearing system. The plant is built up of modules. The plant has positive buoyancy regulated by the buoyancy tanks and a system of stays secured below the surface of the water, so that the plant is held below the surface of the water by the system of stays. The plant employs conventional blades.
Danish Patent 155454 (Hans Marius Pedersen) describes a floating water current power station which consists of a ring-shaped pontoon which by means of a bitt is anchored to anchors on the bottom. All the turbines are replaceable and are arranged on a common beam and can as a unit be swung up to the surface within the area defined by the ring pontoon. The power station may move around the bitt, the upper end of which is connected to a front pontoon and the lower end of which is secured to the anchors.
US Patent 5,440,176 describes a submersible water turbine plant comprising turbines/generators in different combinations suspended below a submerged platform of the tension leg type.

Disclosure and summary of the invention

Thus, according to the invention there is provided a plant for the production of energy from water currents of the type described above and as disclosed in the preamble of the attached patent claims.
The plant according to the invention comprises a floating plant for the production of power from currents in a body of water, comprising a supporting structure supported by a plurality of float members, characterised in that the float members are arranged in pairs on each side of the supporting structure and that supporting arms extend laterally on each side of the supporting structure, each said supporting arm at one end thereof being pivotally attached to the structure, and at the other end thereof being attached to respective generators.
In a preferred embodiment, the supporting arms comprise at least one joint between their first and second ends, so that each supporting arm can be folded about the joint, in order thereby, concurrently with the swinging of the supporting arm about the pivotal connection of its first end with the structure, to raise the respective generator above the surface of the water.
In yet an embodiment, the individual generator unit is pivotally supported about a vertical axis at the free end of the respective elongate support.
In yet an embodiment, the individual generator unit is fixedly mounted at the free end of the respective elongate support.
In yet an embodiment, each generator unit shaft is equipped with at least one rotating member.
In a preferred embodiment, each generator unit is equipped with at least one rotating member rotationally mounted on each side of said generator housing.
In yet a preferred embodiment, the rotating members are counter-rotating.

Brief description of the drawings

Embodiments of the invention are set forth in the attached patent claims, and in the following description with reference to the attached drawings. It should be appreciated that the drawings merely illustrate typical exemplary embodiments and thus should not be regarded as defining the limits of the invention. The same reference numerals are used to indicate the same parts in the drawings, and these are also used in the description below.
Figures 1-3 are perspective views of a second embodiment of the tidal power plant according to the invention with the generators in a dropped position.

Figure 1 is an end view of the plant;
Figure 2 is a side view of the plant; and
Figure 3 is a top view of the plant.

Figure 4 shows the plant in Figures 1-3 seen from one end and with the generators in a retracted position.

Detailed description of embodiments of the invention

The plant according to the invention comprises contra-rotating turbines placed on a steel structure which floats in the water, see Figures 1-4.
The plant comprises a platform 620 having a plurality of buoyancy members 610, preferably one in each corner as can be seen in Figure 3. The requirement of stability, both lateral and longitudinal, is thus met with a minimum of displacement. A plurality of supporting arms 615 extending out from the platform to each side each hold a generator 752 and two turbines on its side, and are secured to a longitudinal pipe which in turn is secured to all four pontoons. The supporting arms are hinged at their point of attachment and about halfway along. Operation of the supporting arms is effected using hydraulics.
The arrangement permits standard, known anchoring using anchor (not shown) and chain 617 in both directions: either one or two anchors in each direction, or that one anchor in each direction holds two platforms. This means that the platforms can be anchored in the longitudinal direction at a desired distance, and so close to each other that turbines run clear of each other. By anchoring several units side by side, the lateral distance will also be adjustable or securable by means of chain.
After anchoring has been completed, chain cutters and anchor winches could be removed and used on the next platform etc. During maintenance and optionally when moving to a maintenance/repair facility (e.g., every third year), the anchor winch is put back and chain is lowered to the bottom. On reinstallation, the chain is winched into the platform and reattached.
Production load from turbines is used to weigh the anchors in each direction. On the opposite side of the anchor load, the chain slack is winched in, and when the water currents turn, the same takes place again on the opposite side. In this way, a secure and stable position is obtained as the current moves in two directions.
If production loads become extremely large, due to possible defects in the control system so that load increases and the anchors perhaps give, this is not a catastrophe. Alternatively, booms could automatically be released to the surface (in the event of defects or problems with the control of turbines or generators). As generator and turbine have positive buoyancy in the water, a great amount of power is not needed to obtain this stop position.
It can also be seen that there are very substantial dynamic forces which act on this kind of turbine, and that this in turn can result in vibrations and fatigue. Compared with a fixed installation on the bottom, a floating platform will obtain considerably greater dampening of vibrations of this type. Thus, the concept is not subject to the same danger of fatigue.
Because the platform floats with little draught (e.g., just 1.5 meters), supporting arms 615 and turbines can easily be moved into the platform side in a "scissored position" relative to one another, and transport or towing in the floating position will be simple.

Claims

A floating plant for the production of power from currents in a body of water, comprising a supporting structure (620) supported by a plurality of float members (610), characterised in that the float members are arranged in pairs on each side of the supporting structure and that supporting arms (615) extend laterally on each side of the supporting structure, each said supporting arm at one end thereof being pivotally attached to the structure, and at the other end thereof being attached to respective generators.
A plant according to claim 1, characterised in that the supporting arms (615) comprise at least one joint (616) between their first and second ends, so that each supporting arm can be folded about the joint (616), in order thereby, concurrently with the swinging of the supporting arm about the pivotal connection of its first end with the structure (620), to raise the respective generator above the surface (S) of the water.
A plant according to claim 1, characterised in that the individual generator unit is pivotally supported about a vertical axis at the free end of the respective elongate support.
A plant according to one or more of claims 1 to 2, characterised in that the individual generator unit is fixedly mounted at the free end of the respective elongate support.
A plant according to one or more of claims 1 to 4, characterised in that each generator unit shaft is equipped with at least one rotating member.
A plant according to one or more of claims 1 to 5, characterised in that each generator unit is equipped with at least one rotating member rotationally mounted on each side of said generator housing.
A plant according to one or more of claims 1 to 6, characterised in that the rotating members are counter-rotating.